osgNature

Rendering of huge amount of trees (osgNature)

Approches to render forest and/or trees in real-time

• Billbords
• 2-crossed-Quads
• Matrix-transformed crossed Quads
• 2-crossed-Quads batched in geometry chunks
• preprocessed billboards based on tree geometry with LODs
• points to display forests and billboards as trunks
  

for reference: from a quick peformance test (using modified osgpointsprite) of rendering with unlit point sprits when not fill limited achieved 39 million points a second, or with just points 91 million/second. Tests carried out on a AlthonXP2600 + GeforceFX5900XT using 100 blocks of 10,000 points stored in osg::Geometry with display lists (VBO's produced slightly lower results!). Same tests carried out with one light on, 32 million point sprites/second and 54 million points/second.

• volume rendering of single or groups of trees
• pre-computed impostors for single trees
• parallax mapping & example code - used both on indivual trees (a fives visible sides of cube?) or as a tree wall and canopy.

First approach generating point trees out of images: (tree with 7000 points made from 128x128 image)

(thoughts: smaller images would lead to less points. quality would no suffer, since it is only an LOD level)

Generate Trees (to populate the forest)

• Arbaro

A great GPL external project here: http://arbaro.sourceforge.net/

Here are 2 scripts for automatically generate textures from the arbaro .xml tree definition, thru povray. TGA texture with alpha is generated, as the corresponding depth-map (for depth-map, you'll have to install megapov. See render_pov_to_textures.sh for more informations). As now, it is still work in progress, but may be usefull for those who want to test forest populated with good-looking trees/textures. (fmarmond@… 2005-01-10) (shell file name appened'.txt' for wiki security reason)
generate_xml_to_textures.sh.txt
render_pov_to_textures.sh.v2.txt (oops, it was an error in the file, new one uploaded 2005-01-13)